Technical Field
The present invention relates to a heat exchanger, a purifier, an electrode-containing pipe, a power generation system, a control method for heat exchanger and a scale removing method.
Related Art
In response to growing global environmental protection, an attention to the power generation using geothermal or industry waste heat resulting from the process of producing an industrial products has increased since there is very little carbon dioxide emissions.
In geothermal power generation method, the following two methods exist. That is, the first method is a flash-cycle system which carries out the power generation by leading the geothermal steam that occurs when a thermal fluid of the gas-liquid state heated at the deep underground is jetted through a well to the ground to the turbine.
In addition, the second method is a binary-cycle system which carries out the power generation by leading a vapor of the working fluid heated by a thermal fluid at a heat exchanger to the turbine.
In the power generation using the binary-cycle system, in recent years, it has been developed for binary power generation system using geothermal water such as spring water as an example of a thermal fluid.
Geothermal water is often present in relatively shallow depth of the underground, and there is an advantage of low installation costs and risks as compared to conventional geothermal power generation. It should be noted that a low boiling point medium having a 100° C. temperature below of the boiling point such as substitute for CFCs (HFE), pentane (C5H12), ammonia is used as the working fluid.
In this binary power generating system, a steam of the low boiling point medium is generated by a heat exchange between the geothermal water introduced into the heat exchanger on the ground and the low boiling point medium also introduced into the heat exchanger. And then, power generation is carried out by rotating a turbine with the steam of the low boiling point medium introduced into the steam turbine.
It is repeated that the steam of the low boiling point medium exhausted from the steam turbine is sent to the heat exchanger again after it is cooled in the condensation machine so that the low boiling point medium is heated by the geothermal water to become the steam of the low boiling point medium.
The technology paying attention to improving the utilization efficiency of the energy of the heat fluid, such as following patent document 1 or patent document 2, is proposed.
For instance, according to the patent document 1, it is indicated to improve the efficiency of the power generating system by changing the evaporation temperature of the thermal fluid, changing the combinations of the vaporizer and the pre-heater, or using the compound liquid of ammonia and water for the operation fluid.
Moreover, according to the patent document 2, it is indicated to supply the hot spring water to the power generating device continuously by using the gushing out power of the hot spring water, the gush power of the hot spring gas, and the vertical interval (difference of potential energy).
The calcium salt of the accident dissolubility that is called a scale might adhere to the inner wall of pipe which is used for the geothermal power generation system because the thermal fluid circulates in the pipe. When this scale adheres in pipe and a long term passes, blocking pipe and the decrease in the heat exchange efficiency are caused.
Therefore, the scale has been removed by adding medicine such as the scale inhibitors or by using a brush to remove mechanically.
However, the prevention of environmental pollution becomes worldwide standard in recent years, and the use of such medicine is withheld voluntarily. Moreover, some damage to the pipe might occur when the scale is mechanically removed by using the brush.
Then, the method of preventing the scale adhesion using the electrolysis processing is developed as a new technique that substitutes for the medicine washing and the brush washing. For instance, according to the patent document 4, the technology that removes the scale by using an anode and a cathode arranged in the electrolysis processor set in circulating passes.
Moreover, according to the patent document 5, the cooling water circulation device having an electrolytic bath storing a cooling water and installed in a cooling water circulation route, a pair of electrode set up in the electrolytic bath, a voltage generator that impresses the voltage between the pair of electrode plates, and an electrolytic device that does an electrolysis processing of the cooling water stored in the electrolytic bath is disclosed.
Patent document 1: Japanese Unexamined Patent Application Publication No. 11-350920
Patent document 2: Japanese Unexamined Patent Application Publication No. 2013-201873
Patent document 3: Japanese Unexamined Patent Application Publication No. 2009-219951
Patent document 4: Japanese Unexamined Patent Application Publication No. 2006-95426
Patent document 5: Re-publication of PCT International Publication WO2006/027825